ONE-ELECTRON ORBITAL DESCRIPTION OF DOUBLET RADICAL BY FSGO METHOD

An attempt has been made to find an orbital description for one-electr on in radical molecules in a doublet state by means of a spherical Gau ssian function basis set. Therefore, the floating spherical Gaussian o rbital (FSGO) method has been employed for this research. The criterio n is experimental geometry if it is possible, and if it is not, the hi ghly elaborate calculated results from literature are taken for compar ison. The best orbital description for those radical has an electron o n bond, such as H-2(+), Li-2(+),He-2(+), is 6G2S(cb)(II), and their co rresponding bond lengths are 1.9953 Da with -0.10% error, 2.0473 Da wi th 0.21% error and 5.9114 Da with 0.53% error, respectively. For those radicals which have one electron centred on one of their atoms, such as CH3, NH3+, CH2+, BH2, the best orbital description is found to be 2 p2s on central atom. The obtained results of bond length (BL) and bond angle (BA) for CH3 are BL = 2.095 Da with 2.70% error and BA = 118.60 degrees; for NH3+, BL = 1.883 Da with -1.34% error and BA = 119.67 de grees; for CH2+; BL = 2.066 Da with -0.03% error and BA = 147.31 degre es with 1.87% error; and for BH2, BL = 2.340 Da with 4.93% error and B A = 131.0 degrees with 0.0% error. It is also found out that the 2p2s orbital behaves as a 3a(1) molecular orbital in Walsh rule for AH(2) a nd AH(3) molecules, and it is responsible for the bending of molecules . There is another type radical which has the centre of one-electron b elonging to the radical near one of the atoms but on the bond, such as LiH+. Our results shows that the model 2p2s correlates to this radica l and gives the bond length 4.164 with 0.52% error. (C) 1998 Elsevier Science B.V. All rights reserved.